Abstract : The main objective of this doctoral thesis is to clarify the existing relations between organisational factors and mobbing in the Ukrainian public sector so to formulate the prevention measures of psychological harassment in the organisational area. To the best of my knowledge, this is the first research that shed light into the psychological harassment as well as on its factors in Ukraine, where the legislation to that matter is inexistent. This thesis has also the ambition to test the impact of individual characteristics of the victim with psychological harassment. To that end, we conducted a research in three steps. Firstly, an analysis of 450 articles has been realised. The aim of that step was to grasp the main organisation factors that influence psychological harassment in a company environment using a precise definition: a minimal harassment length of at least 6 months and a notion of repeatability of the act weekly or monthly. It appeared that five types of factors contribute to the explanation of psychological harassment, namely: work organisation, leadership, the organisational culture and social climate, the compensation and benefit system and organisation changes. Secondly, we led a qualitative exploratory research aiming to refine the results of the literature review with elements that are specific to the Ukrainian area. Twelve semi-structured interviews have been conducted with medical specialists working in obstetrics hospitals located in Kharkiv (Ukraine). The goal of this step resulted in the construction of the research model. Finally, a confirmatory quantitative study helped us to test statistically correlations between fourteen organisational factors and three dimensions of mobbing. Mobbing has been measured through a behavioural method (NAQ, Einarsen et al., 1994). In order to measure the organisation variables, we structured our own survey by inspiring us from several measuring scales tested and validated in previous studies. The transcultural validation steps of one survey of Vallerand (1989) have been applied. Through this quantitative research, 243 participants have been surveyed. Among those, 35% are regular harassment victims during 6 months preceding the research. The analysis brings out that the fact of being a man increases the likelihood of being harassed. When it comes to organisational factors, it turns out that role conflict, work conflict, social support and decision authority are all major determinants in moral harassment in the Ukrainian context.